CAREER: Taphonomy and Evolution of Theropod Dinosaur Reproduction

现存鸟类的繁殖在产蛋速度、蛋的大小和形状、蛋壳的微观结构、巢的形式、孵化方法以及亲代照料的方式和普遍程度等方面与其他现代脊椎动物有明显的不同。鸟类和其他现存脊椎动物之间的差异引发了关于这种独特的繁殖方式是如何以及何时进化的问题。它起源于飞行之前还是之后？从鸟类进化而来的食肉兽脚亚目恐龙在繁殖方面与它们的恐龙亲戚或现代鸟类更相似吗？中生代恐龙的繁殖和生活史策略对它们的成功有多重要？该研究通过记录中生代从恐龙到鸟类的生殖特征进化来解决这些问题。该研究包括四个阶段：1)研究现代鸟类和鳄鱼的筑巢地点，寻找有助于解释恐龙遗址的属性；2)白垩纪兽脚亚目恐龙筑巢地点的调查；3)基于野外、实验室和博物馆研究构建繁殖特征的进化史；4)比较兽脚亚目恐龙、其他恐龙和活着的产卵脊椎动物的生活史策略。这项研究的优势包括一个跨学科的团队，他们在埋藏学（化石保存的研究）、蛋壳结构和现代鸟类的筑巢行为方面具有专业知识，以及无与伦比的现代和化石样本。现代的筑巢地点代表了鳄鱼和鸟类，它们表现出广泛的繁殖行为。中生代恐龙样本包括来自蒙大拿州和爱达荷州白垩纪的四种蛋；这四种类型的蛋代表了北美唯一的兽脚亚目恐龙蛋。现代筑巢层的研究为解释化石筑巢位置提供了框架。从现代鳄鱼和鸟类的研究中产生的数据将有助于识别影响化石保存的模式和过程。广泛的田野调查、对恐龙蛋的实验室分析和特殊的化石样本相结合，将为恐龙蛋的保存和兽脚亚目恐龙的繁殖行为提供新的见解。鉴定新的卵子特征和解决有关兽脚亚目恐龙生殖行为的争议问题将加强我们对进化的理解。记录鸟类及其兽脚亚目恐龙祖先的繁殖进化史，将有助于深入了解鸟类的起源。将鳄鱼目动物、恐龙和鸟类的现代和灭绝的生命史策略进行比较，将增加目前对恐龙生态学的理解，在宏观进化的尺度上检验生命史理论，并允许对整个中生代恐龙整体成功的潜在因素进行评估。教育目标包括将研究观察和解释纳入大学课程，并通过研讨会和实地考察参与为蒙大拿州农村科学教师提供专业发展。此外，该项目将为两名硕士和八名本科生提供研究机会。最后，Varricchio担任2009年夏天在蒙大拿州立大学举行的第四届恐龙蛋和恐龙蛋国际研讨会的主持委员会主席。这次会议为传播研究成果提供了一个极好的机会，同时促进了生物学家和古生物学家之间关于鸟类和恐龙繁殖进化的思想交流。

TAPHONOMY AND EVOLUTION OF THEROPOD DINOSAUR REPRODUCTION David J. Varricchio Reproduction in living birds differs markedly from that of other modern vertebrates in the rate of egg production, egg size and shape, microscopic structure of the eggshell, nest form, method of incubation, and the manner and prevalence of parental care. The disparity between birds and other living vertebrates raises questions as to how and when this unique reproductive style evolved. Did it originate before or after the achievement of flight? Were the carnivorous theropod dinosaurs from which birds evolved reproductively more similar to their dinosaur relatives or to modern birds? How important were the reproductive and life history strategies of Mesozoic dinosaurs to their success? The proposed research addresses these questions by documenting the evolution of reproductive traits through the Mesozoic from dinosaurs to birds. The investigation consists of four phases: 1) study of modern bird and crocodile nesting localities for attributes that would help interpret dinosaur sites, 2) investigation of Cretaceous theropod dinosaur nesting sites, 3) construction of an evolutionary history of reproductive traits based on field, laboratory, and museum study and 4) comparison of the life history strategies among theropod dinosaurs, other dinosaurs, and living egg-laying vertebrates. Strengths of this study include an interdisciplinary team with expertise in taphonomy (the study of fossil preservation), eggshell structure, and the nesting behavior of modern birds, as well as an unsurpassed suite of modern and fossil samples. Modern nesting localities represent both crocodilians and birds that exhibit a wide array of reproductive behaviors. The Mesozoic dinosaur sample includes four egg types from the Cretaceous of Montana and Idaho; these four egg types represent the only in place theropod dinosaur eggs from North America. The study of modern nesting horizons provides the framework for interpreting fossil nesting localities. Data generated from the studies of modern crocodilians and birds will allow recognition of patterns and processes affecting fossil preservation. The combination of extensive fieldwork, laboratory analysis of eggs, and the exceptional fossil sample will provide new insights on egg preservation and the reproductive behavior of theropod dinosaurs. Identification of new egg characters and resolution of controversial issues regarding theropod reproductive behavior will strengthen our evolutionary understanding. Documentation of the evolutionary history of reproduction in birds and their theropod dinosaurs ancestors, will provide insight into the origination of birds. Comparison of modern and extinct life history strategies among crocodilians, dinosaurs, and birds will increase current understanding of dinosaur ecology, test life history theory on a macroevolutionary scale, and permit evaluation of factors potentially contributing to the overall success of dinosaurs throughout the Mesozoic. Educational goals include incorporation of research observation and interpretation into university courses and professional development for rural Montana science teachers through workshops and fieldwork participation. Additionally, the project will support research opportunities for two masters and eight undergraduate students. Finally, Varricchio serves as host committee chair for the 4th International Symposium on Dinosaur Eggs and Babies to be held at Montana State University in the summer of 2009. This meeting provides an excellent opportunity for dissemination of the research results, while facilitating greater exchange of ideas between biologists and paleontologists regarding the evolution of bird and dinosaur reproduction.